LCA Food 2012 in Saint Malo, France! - Manifestations et colloques ...

GROUP 4, SESSION B: CROP PRODUCTION SYSTEMS 8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
120. Life cycle assessment of various fertilisation systems in open field
vegetable production, Flanders, Belgium
Reindert F. Heuts * , Jelle Van Loon, Eddie Schrevens
Katholieke Universiteit Leuven, Research group DQM, Div. M3-BIORES, Dep. of Biosystems, Celesti-
jnenlaan 200E b2411, BE-3001 Heverlee, Belgium, Corresponding author. E-mail: Reindert.Heuts@biw.kuleuven.be
In Flanders, many farmers and horticultural growers wonder how they can lower the residual nitrate on their
parcels to satisfy the fertiliser regulations set up by European legislation. Currently this threshold is set at a
residual soil nitrate value of 90 kg/ha; for many farmers a limit hard to comply. In open field vegetable production
like leek and cauliflower an overuse of fertiliser is very common. In this sector, less then 40% of the
cultivated parcels were found under the imposed limit (Vlaamse Milieumaatschappij (VMM) 2006). One of
the reasons of this excess on fertiliser application is the need of farmers to procure a good yield with a high
quality to be competitive on the domestic market. Lowering the nitrogen application rate however, with current
recommended fertiliser schemes (i.e. KNS-system (Lorenz et al. 1985)), does not yet give sufficient
guaranties to uphold these demanding standards.
In 2010 an experiment has been set up to monitor and evaluate the influence of different fertiliser application
rates and strategies on the growth, yield and quality of a cauliflower crop, and with a special emphasis on the
amount of nitrate leaching to soil and surface water. The experiment consists of 8 plots, treated with two
different fertiliser doses and two application strategies, to create a two by two completely randomised factorial
design, replicated in two blocks. Each plot was fitted with an impermeable foil to capture and sample the
drainage. Destructive and non-destructive plant samples were taken to follow up growth evolution of the
plant and at harvest measurements were done to evaluate the overall product quality.
The experiment was chosen in such a way that a comparison could be made between common cultivation
practices and ‘improved’ management schemes developed with the intention of lowering the nitrate leaching.
For the common practices a broadcast fertilisation with calcium ammonium nitrate is assumed and, based on
the recommendation of the KNS-system, a split fertilisation of 150 kg N/ha at planting and 240 kg N/ha 7
weeks later is applied (i.e. the high dose), the mineral N present in the soil profile included. In attempt to
achieve lower nitrate leaching, the improved strategies consist of: a) the same broadcast split fertiliser application
but with a low dose of 50 kg N/ha at planting and 100 kg N/ha 7 weeks into the growing season, b) a
weekly fertigation of ammonium nitrate with the high dose, and c) the same fertigation scheme with the low
dose.
As expected, differences in yield have been found among the various tested fertilisation systems (i.e. broadcast
high yielded 70,99 ton/ha, broadcast low 55.26 ton/ha, fertigation high 67.28 ton/ha and fertigation low
53.44 ton/ha). When aiming only at high productivity, one would not distinguish between the broadcast and
fertigation application of fertiliser, but with current pressure on the environment more objectives come into
consideration. For this reason a life cycle assessment (LCA) has been carried out (Guinee et al. 2002). Comparing
each fertilisation system the LCA focuses on the differences in input loads and their corresponding
environmental impacts in terms of resource depletion, global warming, toxicity, acidification and eutrophication
with special attention to nitrate leaching. This way policy makers and farmers can consider to what extent
the quantity or quality is influenced by a reduction in fertilisers and/or different treatment inputs regarding
their impact on the environment. In this way, the LCA supports decision making regarding optimisation
of the fertilisation system and adaptation to severe constraints about energy demand and emissions to air,
water and soil.
In contrast with expectations, no large differences in impact have been found and even more surprising, the
fertigation treatments did not score all too well. The nature of environmental impact with respect to the used
fertilisation system, however, did change. This suggest that, even though a progressive split fertiliser application
and fertigation are perceived as environmental conserving techniques, the problem is more complex and
the larger context in which the farming activity takes place has to be considered in first instance before being
able to make proper unambiguous fertiliser management recommendations.
References
Guinee, J. B., Gorrée, M., Heijungs, R., Huppes, G., Kleijn, R., de Koning, A., van Oers, L., Wegener
Sleeswijk, A., Suh, S., Udo de Haes, H. A., de Bruijn, H., van Duin, R., Huijbregts, M. A. J., 2002.
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